Two assistant teachers say they were fired from an East Side day-care center for blowing the whistle on an abusive colleague who would smack toddlers so hard their “feet would leave the ground.”

In a lawsuit filed in Manhattan Supreme Court, Elizabeth Reiback and Annette Ottley said they saw teacher Joanne Pinkard “constantly hit toddlers and tots on their heads, feet, buttocks and hands with objects such as books, tissue boxes and shoes.”

“These two plaintiffs saw things that revolted them and made them feel the kids they cared for were in danger,” said their lawyer, Michael Shen, who claims the teachers were “retaliated against” after reporting the abuse at the Children’s All Day School on East 60th Street.

“They spoke out and were slapped down,” Shen said.

Pinkard, 45, and the school’s director, Roni Hewitt — who the suit charges asked employees to lie about the alleged abuse to state investigators — refused to comment.

Ottley started working at the school, which has about 85 students between the ages of 6 months and 6 years and where parents pay about $1,400 a month, in November 1995. Reiback started 10 months later.

“She would often grab a toddler by the arm and smack the toddler on the rear so forcefully that the toddler’s feet would leave the ground,” the papers charge.

In April 1998, the papers charge, Pinkard hit a 2-year-old girl on the head with a spoon so hard “the noise resounded throughout the room.”

Pinkard punished another toddler by leaving him in the yard alone, and when he tried to follow her back in, she slammed the door on his hand, fracturing his finger, the papers charge.

The teachers said they kept quiet because Pinkard was good friends with Hewitt, and they were worried they’d be fired if they spoke out. They broke their silence in July 1998, when they learned they were legally obligated to report any abuse.